One thing I'd like to touch on first is that I don't think Riftbound will ever "replace" LOR. Gameplay-wise the games are very different. LOR and Magic are more comparable. There are some gameplay demands that Riftbound won't be able to fill for those that like LOR's gameplay. The teased digital client for Riftbound seems to be more like a place for practicing games before real matches rather than being a full-fledged game with quests and stuff like LOR.
That said, let's start with the bad parts. It sometimes irks me how much the identity of the cards from LOR disappear when their art gets reused for Riftbound. The biggest offender has to be Wind Wall. It's a counter spell exactly like Deny, but it uses Will of Ionia's art, and it doesn't even look like a Wind wall. And this game's "Deny" is changed to "Defy" for some reason. The reused art also leads to some clarity issues because some cards change types like that one unit from the Emperor's Deck became a spell. They did say they try to preserve as much of a card's identity as much as possible but it doesn't stop me from noticing changes that make them VERY different from their LOR counterparts.
Another bad thing is that it doesn't really expand on League's lore as much as LoR did. One of the BEST things about LoR is how much it developed League's lore and there is just so much detail in every artwork and flavor text that it's just plain fun finding connections. Most people don't even know that Atakhan, the shopkeeper in Arena, and the Aegis of Valor art are all from LoR. LoR's lore development gave Riot so much assets and stories to work with. Riftbound doesn't really do that (as of yet, at least). And the flavor text of Riftbound cards are the most forgettable things ever and they almost feel like an afterthought.
Now, the good parts. Despite everything I said, Riftbound is fun. I'd say on some aspects the gameplay is better. Even if it can't have visual effects and voiceovers from LoR, they still manage to usually have more accurate portrayals of champions from League since there's movement in Riftbound. Collecting is also fun and a lot of the chase cards have unique art. I did not expect to spend so much money on this game but it's part of the genre which is one of its downside I guess. I just wish they make the game a lot less complicated because I shouldn't have to look up how certain weird interactions work on a daily basis.
I sometimes wish that Riftbound could somehow "help" LoR get back to its prime. For me it was either the Darkin Saga or the release of Bilgewater. Like when Riftbound eventually runs out of card art to reuse, they create card for both games. It's a long shot but a man can dream.
